This invention relates in general to refractory-lined tubes, pipes or cylinders, and more particularly to a method for producing a refractory-lined cylinder by an exothermic reduction reaction, such as aluminothermic reduction.
Tubes, pipes, cylinders, and tanks lined with acid-resistant, corrosion-resistant or abrasion-resistant materials intimately bonded to the metal shell are required in many industrial applications. The shells of some tanks used in the oil industry, for example, are protected by a cured mixture of furnace cement and sand containing short asbestos fibers. The interiors of steel pipes and tanks exposed to corrosive water, salt solutions, or oils containing sulfur compounds are also often coated with cement to inhibit the attack on the steel. In cases where tanks are not subjected to high abrasive wear, but still require protection from an agressive environment, expensive stainless steels are often used in place of carbon steel.
In other applications, glass lined vessels and pipes are used despite their obvious disadvantages and limitations. Thin impervious linings for steel vessels are also obtained through the use of vitreous enamels. This material is essentially a borosilicate glass containing fluorides which is finely ground, suspended in water or an organic solvent, and applied to the surface of the steel by dipping or spraying. The assembly is then dried by warming and finally heated in a furnace to near 1600.degree. F. to melt the enamel so that the particles flow together to form a continuous coat. The operation is often repeated to obtain a sufficiently thick coat. In addition to the complicated and tedious procedure, the substrate steel must be carefully cleaned by degreasing and pickling to assure satisfactory bonding. These treatments are costly and time consuming.
In steelmaking operations, tuyeres and lances are lined with high alumina or mullite linings, which are held in place by refractory cement, to reduce damage from abrasion. The linings are expensive and subject to breakage prior to and during installation in the tuyeres.
We are aware of the following prior art concerning aluminothermic welding processes and centrifugal casting:
Adams U.S. Pat. No. 1,796,819 PA1 Touceda U.S. Pat. No. 2,011,955 PA1 Carpenter et al. U.S. Pat. No. 2,515,191